The embodiment relates to formulation of grape-based products such as, but not limited to, juice, juice-blended beverages, and wine containing a significant amount of bioavailable calcium as well as to processes for the manufacture of the products. The field encompasses the production, storage and distribution of stable calcium-fortified purple, red and white grape juice and juice drinks, in shelf-stable, refrigerated, frozen and concentrate forms. Beverages covered include grape-based liquids blended with non-grape liquids.
Calcium is an essential mineral in the human diet for the preservation of human health. Calcium has been established as a key nutrient for skeletal rigidity; it is also known to impact metabolic, muscular, neurological, circulatory, and enzymatic processes. Calcium deficiency is a contributing cause of osteoporosis, a debilitating bone disease marked by a loss of bone mass.
Calcium is naturally found in many foods. The primary source of bioavailable calcium is milk and, more generally, dairy products. As people enter early adulthood, their consumption of dairy products tends to decrease. This may lead to a state of chronic calcium deficiency. This trend is particularly found with young women and could contribute to their high rates of osteoporosis development in later life. Additionally, many people are, or become, lactose intolerant as they age, thus reducing their ability to obtain natural, traditionally rich sources of this mineral.
Therefore, many alternate sources of food, drink, and supplements are currently being fortified with various organic and inorganic calcium salts. These alternate sources include pills, powders, food products, as well as a variety of fruit and non-fruit based juices and beverages. Many plaguing problems surround the provision of organoleptic qualities and bioavailability of these calcium-fortified sources. A common complaint with respect to fortified beverages is the relative insolubility of some of the added calcium salts, intolerable precipitation of solids, and a xe2x80x9cchalkyxe2x80x9d feeling in the mouth upon drinking. Additionally, undesirable flavors and shelf instability contribute to a poor food product.
The fortification of various liquids with calcium, including orange, apple and other juices and beverages is an art currently practiced by juice and beverage manufacturers. Patents describing calcium fortification of fruit juices include several granted to Heckert and assigned to the Proctor and Gamble Company (for example, U.S. Pat. No. 4,722,847). These patents disclose calcium-citrate-malate (CCM) technology and teach that various calcium citrate and malate compounds, when combined in accordance with disclosed processing methods, will produce stable, fortified juices containing calcium levels at least equivalent to those normally occurring in milk (i.e., 350 mg/8 fl. oz.).
U.S. Pat. No. 4,740, 380 to Melachouris et al. discloses a calcium-fortified acidic beverage formulated using various calcium sources. U.S. Pat. No. 6,106,874 to Liebrecht et al. discloses a calcium-fortified nutritional beverage, which can be made from single strength juice. Calcium sources therein are natural milk mineral and Gluconal CAL(copyright) (manufactured by Glucona America).
Calcium fortification of grape-based beverages is especially challenging. The predominant organic acid in grape-based liquid (e.g. juice, wine, etc.) is, uniquely among fruit-derived liquids, tartaric acid. At pH levels above 2.8, tartaric acid will chemically dissociate into tartrate, bitartrate and hydrogen ions. As the pH of grape juice increases, the dissociation of tartaric acid becomes progressively more favored. Across the typical pH range of about 2.8 to about 3.9 for purple, red and white grape juices from Vitis labrusca, V. vinifera, and V. labrusca x V. vinifera hybrid grapes, the availability of tartrate ions for reaction with any added calcium to form insoluble crystalline calcium tartrate, is very high. Indeed, at relatively high pH and without the presence of calcium, potassium bitartrate crystals or xe2x80x9cargolxe2x80x9d in juice (or xe2x80x9cwine stonesxe2x80x9d in wine) may be formed due to the naturally occurring concentration of potassium in grape-based product. This is commonly found in winemaking and the pertinent literature is abundant in addressing ways to solve this problem.
The formation of calcium tartrate crystals in grape-based liquids is known from past research on wines. This formation is dependent, for example, on the pH of the beverage, the storage temperature of the calcium plus beverage mixture, the presence of inhibitors, the ionic strength of solution, agitation of solution, and the length of time that the mixture is held in storage. Abgueguen and Boulton, (1993); McKinnon, 1993. Formation of calcium tartrate crystals may occur instantly upon the cooling of a pasteurized juice-calcium mixture, Alternatively, crystals may not occur for a substantial period of time. However, because calcium tartrate crystals have very low solubility in aqueous solutions such as grape juice, once formed, these crystals will tend to remain as an insoluble precipitate rendering the beverage organoleptically unacceptable with significantly diminished bioavailable calcium. After initial nucleation of these crystals, they will generally grow in size until the point of solution saturation is reached.
In accordance with a first embodiment of the present invention, a method of making a fortified, tartaric acid-containing product is provided. The product is fortified with a predetermined amount of bioavailable calcium and the product is essentially free of tartrate precipitates. A tartaric acid-containing precursor is provided. The concentration of tartaric acid in the precursor may be between approximately 0.005 g per 100 mls and approximately 1.31 g per 100 mls. The precursor may be a grape-based liquid and may be derived from colored or white grapes. The predetermined amount of bioavailable calcium may be between 8% and approximately 35% of required daily intake for a human. The tartaric acid concentration of the precursor is adjusted to form an adjusted precursor. In an embodiment, the measured, adjusted tartaric acid concentration might be no greater than 0. 17g per 100 mls. An additive comprising a calcium-based compound is mixed with the adjusted precursor to make the fortified product. The compound may be calcium gluconate, a variety of other compounds or mixtures thereof. The fortified product, when stored at approximately 70xc2x0 F. may remain essentially free of tartrate precipitate for at least sixteen weeks.
In other embodiments, fortified, tartaric acid-containing products processed by the methods described above are provided.
In a further embodiment, another method of making a fortified, tartaric acid-containing product is provided. In this embodiment, the precursor has between approximately 0.005 g per 100 mls and approximately 0.26 g per 100 mls of tartaric acid. The precursor is mixed with a predetermined amount of calcium gluconate. The bioavailable calcium in the resulting product is no more than approximately 20% of required daily intake of calcium for a human. In further embodiments, the resulting product is provided.
The adjusted precursor may be formed by adding a second precursor to a liquid tartaric acid-containing precursor. The second precursor may be single strength juice. Water may alternatively be added during adjustment; the adjusted tartaric acid concentration might be no greater than approximately 0.08 g per 100 mls. The calcium-based compound may be calcium lactate.
In yet another embodiment, a method is provided to make a fortified, tartaric acid-containing product with bioavailable calcium in an amount equaling approximately 35% of required daily intake for a human. The tartaric acid concentration of a precursor derived from colored grapes is adjusted to form an adjusted precursor and calcium gluconate is mixed with the adjusted precursor.
In yet another embodiment, a method is provided to make a fortified, tartaric acid-containing product with bioavailable calcium in an amount equaling between approximately 8% and approximately 35% of required daily intake for a human. The tartaric acid concentration of a precursor derived from white grapes is adjusted to form an adjusted precursor and calcium lactate is mixed with the adjusted precursor.
Still other embodiments provide product made by both of the latter embodiments.